CN110632684B

CN110632684B - Super-surface sparse aperture lens

Info

Publication number: CN110632684B
Application number: CN201911000828.6A
Authority: CN
Inventors: 胡敬佩; 刘铁诚; 曾爱军; 朱玲琳; 黄惠杰
Original assignee: Shanghai Institute of Optics and Fine Mechanics of CAS
Current assignee: Shanghai Institute of Optics and Fine Mechanics of CAS
Priority date: 2019-10-21
Filing date: 2019-10-21
Publication date: 2021-06-01
Anticipated expiration: 2039-10-21
Also published as: WO2021077485A1; CN110632684A

Abstract

The super-surface sparse aperture lens comprises a plurality of sub-lenses arranged according to a certain sequence, each sub-lens comprises a plurality of microstructures and a substrate supporting the microstructures, and all the sub-lenses jointly form the super-surface sparse aperture lens. The phase information corresponding to the super-surface sparse aperture lens can be determined by the wavelength of incident light and the focal length of the lens. By utilizing the sparse aperture technology, the spatial resolution which is the same as that of a large-aperture optical system can be obtained through the sub-lens array system, so that the preparation difficulty and the processing cost of the large-aperture super lens are reduced. The invention has high application value in the aspects of miniaturization and integration of a microscopic imaging system and an endoscopic imaging system.

Description

Super-surface sparse aperture lens

Technical Field

The invention belongs to the technical field of optics, and particularly relates to a super-surface sparse aperture lens.

Background

The super-surface lens is an ultrathin two-dimensional array plane formed on the basis of a sub-wavelength microstructure, is a two-dimensional diffractive optical element, has the potential of plane integration, achromatism, exceeding diffraction limit and the like due to the effective regulation and control of the amplitude, phase and polarization state of electromagnetic waves, and becomes a research hotspot in the field of current diffractive optics and nanophotonics, but the super-surface lens still has the problems that the aperture is small, the manufacture of large-aperture equipment cannot be realized and the like.

Disclosure of Invention

The invention aims to provide a super-surface sparse aperture lens, which solves the problem that the conventional super-surface lens cannot realize the manufacture of large-aperture equipment, reduces the preparation difficulty of the large-aperture super lens, reduces the load volume and weight, can obtain the spatial resolution which is the same as that of the large aperture by a sub-lens array, and has high application value in the aspects of improving the resolution of a super-surface optical lens system, improving the preparation efficiency of the super-surface lens and the like. In order to achieve the above purpose, the technical solution of the invention is as follows:

the super-surface sparse aperture lens is characterized by being formed by arranging a plurality of super-surface sub-lenses with the same structure on a substrate according to a certain spatial position, wherein each super-surface sub-lens is formed by arranging a plurality of micro-structure pixel units with the same structure.

The microstructure pixel unit is composed of a cuboid and a cuboid annular structure surrounding the cuboid, the cuboid annular structure is an etched microstructure, and the cuboid is a reserved microstructure.

The super-surface sparse aperture lens, wherein the certain spatial location comprises Annulus, Double, Golay3, Ring6, Golay6 or Tri-arm 7.

The super-surface sparse aperture lens is characterized in that the microstructure pixel unit is a metal super-surface microstructure or a medium super-surface microstructure capable of regulating and controlling phase change.

The super-surface sparse aperture lens is characterized in that the substrate is prepared from silicon dioxide, aluminum oxide or other light-transmitting self-supporting media.

The preparation method of the super-surface sparse aperture lens is characterized by comprising the following steps of:

1) designing a sub-lens array with a certain spatial position;

2) calculating the phase distribution of the sub-lenses and generating a phase map, wherein the formula is as follows:

wherein

Is the phase corresponding to the center of the micro-structure pixel unit cuboid, x is the horizontal coordinate of the center of the micro-structure pixel unit cuboid, y is the longitudinal coordinate of the center of the micro-structure pixel unit cuboid, m is any integer, f is the focal length corresponding to the super-surface sub-lens,λ is the wavelength of the incident light;

3) simulating microstructure pixel units with different structural parameters to obtain phase regulation curves and transmittance curves of the microstructure units with different parameters, and optimizing the structural parameters of the microstructure to enable the microstructure to achieve the phase regulation capability of 0-2 pi and ensure the uniformity of transmittance;

4) carrying out equal-proportion discretization on the generated phase map according to requirements, and selecting the corresponding microstructure pixel unit size to generate a microstructure size map file;

5) and (3) realizing the exposure and transfer of the microstructure by using electron beam exposure or laser direct writing exposure and etching processes to obtain the required super-surface sparse aperture lens.

Compared with the prior art, the invention has the following technical effects:

the invention can obtain the spatial resolution which is the same as that of the large-aperture optical system through the sub-lens array system, thereby reducing the preparation difficulty and the processing cost of the large-aperture super lens. The invention has high application value in the aspects of miniaturization and integration of a microscopic imaging system and an endoscopic imaging system.

Drawings

FIG. 1 is a three-dimensional schematic diagram of a super-surface sparse aperture lens structure according to the present invention;

FIG. 2 is a schematic view of a microstructure pixel unit according to the present invention;

FIG. 3 is a block diagram of a super-surface sub-lens of the present invention;

FIG. 4 is a light intensity distribution diagram of a super-surface sub-lens focusing light spot in a transverse section and a longitudinal section, wherein a is a light intensity distribution of the transverse section, and b is a light intensity distribution of the longitudinal section;

FIG. 5 is a diagram of the super-surface sparse aperture lens structure (taking Golay3 structure as an example) according to the present invention;

FIG. 6 is a schematic diagram of super-surface sparse aperture lens imaging;

FIG. 7 original image;

FIG. 8 is an image simulation analysis diagram of a super-surface sparse aperture lens.

Detailed Description

The present invention is further illustrated by the following examples and figures, but should not be construed as being limited thereby.

Referring to fig. 1, a super-surface sparse aperture lens 101 has an array structure formed by arranging and combining a plurality of super-surface sub-lenses 102 having the same structure according to a certain spatial position, the super-surface sub-lenses are formed by arranging 104 discrete micro-structure pixel units 103 on a substrate, and the substrate is made of silicon dioxide.

Taking a metal super-surface microstructure pixel unit as an example, as shown in fig. 2, the microstructure pixel unit 103 is a rectangular parallelepiped structure, the microstructure material is aluminum, the length and the width (a and B) are both set to be 0.6 micrometers, and the height (C) is set to be 0.8 micrometers. The microstructure pixel unit 103 is composed of a cuboid 201 and a cuboid annular structure 202 surrounding the cuboid 201, the cuboid annular structure 202 is an etched microstructure, and the cuboid 201 is a reserved microstructure.

The generation method of the super-surface sparse aperture lens comprises the following steps:

1) designing an array of sub-lenses 102 at a certain spatial position;

2) according to the calculation formula:

calculating the phase distribution of the sub-lenses and generating a phase map, wherein

The phase position corresponding to the center of the cuboid 201 of the microstructure pixel unit 103 is shown, x is the horizontal coordinate of the center of the cuboid of the microstructure pixel unit, y is the longitudinal coordinate of the center of the cuboid of the microstructure pixel unit, m is any integer, f is the focal length corresponding to the super-surface sub-lens, and lambda is the wavelength of incident light;

The structure diagram of the super-surface sub-lens obtained through exposure or transfer is shown in fig. 3, the number of the microstructures in the horizontal and vertical directions is 27, the total number of the microstructures is 729, the microstructures are arranged in an array type period, and the period of the microstructures is 0.8 micrometer. And (3) performing simulation analysis on the optical performance of the super-surface sub-lens, wherein the light intensity distribution of the focused light spot passing through the super-surface lens is in the transverse section and the longitudinal section, as shown in fig. 4a and 4b, wherein the full width at half maximum of the transverse section is 1.08 micrometers, and the full width at half maximum of the transverse section is 1.782 micrometers.

The super-surface sparse aperture lens can be obtained by arranging the super-surface sub-lens structures at certain sequence of spatial positions, and the certain spatial position arrangement combination comprises the structures of Annulus, Double, Golay3, Ring6, Golay6, Tri-arm7 and the like. In this embodiment, the structure of the Golay3 super-surface sparse aperture lens is shown in fig. 5, and includes three super-surface sub-lenses 102 with identical structures, and arranged in a Golay3 array type. The three sub-lenses together form the aperture of the sparse lens, which can produce an equivalent aperture that is the Golay3 array circumscribed circular aperture 501.

The imaging process of the super-surface sparse aperture lens is described in detail in example 1.

Example 1:

taking the imaging optical path of fig. 6 as an example, the original 601 is a 512 × 512 resolution plate picture, and as shown in fig. 7, the super-surface sparse aperture lens 101 is arranged in a Golay3 structure. The CCD 701 images the object at the imaging position and transmits the image to the computer 702, wherein the distance d1 between the original 601 and the lens 101 is 1500 micrometers, and the distance d2 between the image 701 and the lens 101 is 10.067 micrometers.

The imaging steps are as follows:

1) adding the super-surface sparse aperture lens 101 into a light path, and imaging an object;

2) the acquired image is restored by the computer 702 to obtain a final restored image, as shown in fig. 8, it can be seen that the super-surface sparse aperture lens can obtain the same imaging result as the large aperture lens.

Claims

1. The super-surface sparse aperture lens (101) is characterized by being formed by arranging a plurality of super-surface sub-lenses (102) with the same structure on a substrate (104) according to a certain space position, wherein each super-surface sub-lens (102) is formed by arranging a plurality of micro-structure pixel units (103) with the same structure.

2. The super-surface sparse aperture lens of claim 1, wherein the micro-structured pixel unit (103) is composed of a cuboid (201) and a cuboid ring structure (202) surrounding the cuboid (201), wherein the cuboid ring structure (202) is an etched microstructure, and the cuboid (201) is a retained microstructure.

3. The super-surface sparse aperture lens of claim 1, wherein the certain spatial location comprises Annulus, Double, Golay3, Ring6, Golay6, or Tri-arm 7.

4. The super-surface sparse aperture lens of claim 1, wherein the microstructure pixel units (103) are metal super-surface microstructures or dielectric super-surface microstructures capable of regulating and controlling phase change.

5. The super-surface sparse aperture lens of claim 1, wherein said substrate (104) is made of silica or alumina.

6. A method of making a super-surface sparse aperture lens of any of claims 1 to 5, comprising the steps of:

1) designing an array of sub-lenses (102) at a spatial location;

wherein

The phase position corresponding to the center of a cuboid (201) of a microstructure pixel unit (103), x is the horizontal coordinate of the center of the cuboid of the microstructure pixel unit, y is the longitudinal coordinate of the center of the cuboid of the microstructure pixel unit, m is any integer, f is the focal length corresponding to the super-surface sub-lens, and lambda is the incident light wavelength;

3) simulating the microstructure pixel units with different structural parameters to obtain phase regulation curves and transmittance curves of the microstructure pixel units with different structural parameters, optimizing the structural parameters of the microstructure to achieve the phase regulation capability of 0-2 pi and ensure the uniformity of transmittance;